Chemoselectivities in the platinum-catalyzed hydrative carbocyclizations of oxo-alkyne-nitrile functionalities

Abstract

Two new hydrative carbocyclizations of oxa-alkyne-nitrile functionalities are reported to produce distinct nitrogen-containing heterocycles. Protracted heating of oxoalkynyl nitrile substrates with PtCl2/CO/H2O in hot 1,4-dioxane gave 2,3-dihydro-1H-pyrido[1.2-b]-isoquinolin-4(6H)-ones. In this hydration reaction, dicarbonyl nitrile intermediates were isolated efficiently after a brief period, and they were subjected to an NHC-based crossed benzoin coupling to give spiro alcohols that further reacted with TfOH to give spiro[indene-2,2′-piperidine]-1,6′(3H)-diones. © 2011 American Chemical Society.